In the exploration and development of offshore petroleum reserves, it is sometimes necessary to erect platforms located miles off shore. These platforms form a base on which drilling, exploration and storage activities can occur and the majority of these platforms have legs or other types of support structure extending down into the water. To transport men and material to and from these platforms, vessels are used and docked along side during unloading operations. Although small vessels are sometimes used in these operations, normally the vessels are quite large. When contact occurs between these vessels and the platform leg, damage can occur to either the structure or the vessel.
To protect these platforms from damage due to contact by vessels operating near the platforms, systems attached to the platform adjacent the water level have been designed and operate to fend off vessels and absorb shocks caused when the vessels come into contact with the platform legs.
One system, which has been used for years in the industry, is known as the Lawrence Allison System. This system utilizes a vertically standing piece of pipe or other structural member supported from the platform at the water level. The pipe typically has its upper end supported from the leg of the platform at a position above the high tide level and its lower end connected to the platform at a position below the low tide level. This system further utilizes a plurality of rubber vehicle tires with the pipe exiting through the center of the tires to form a tire stack to absorb the vessel's shocks. Some of these systems leave the outer surfaces of tires exposed and some have a cylindrical metal skin or can supported around the outside of the tires and spaced away from the central pipe by the tires. In the latter systems, the tires resiliently separate the outer contact skin from the inner central support.
In some other prior art systems, the outer can or contact surface is resiliently separated from the central structural support by a pre-formed rubber element. In one such system, the outer protective shield or can and the central support are coaxially positioned by using a solid rubber element which extends the length of the outer shield and occupies less than 360.degree. but at least 180.degree. of the annular space formed between the outer shield and the central support. In these systems, the rubber element has a constant radial thickness and are positioned in the annular space on the side from which contact with the approaching vessels normally occurs.
Although prior art bumper systems have performed satisfactorily, in many ways unappreciated by the industry, their design has contained aspects which are redundant and which add to the overall cost of the system. For example, these prior art systems fail to appreciate and/or accommodate the savings in design cost and size reductions which are accomplished by taking into account the limited direction from which contact forces are applied. Further, these prior art systems utilize complicated manufacturing and fabrication techniques which are unnecessary.